- There's a cousin Joanna that's definitely crazy.
- Who told you?
- Dinah.
- Well, Dinah should know.

6 seconds sound clip from the The Philadelphia Story movie soundboard.

You can hear this line at 00:36:18 in the Blu-ray version of the movie.

Quote context

[...]

- Another place, Edward.

- Yes, madam. (2)

- I'm afraid I don't understand.

- You never have. But you came anyway, didn't you?

- Oh. Still justice with her shining sword, eh, Daughter?

- Who's on the spot?

- We are, thanks to you... Uncle Willie.

- How long will you be researching?

- Not long, if I can find the right books. It's family history and stuff like that.

- There's a cousin Joanna that's definitely crazy.

- Who told you?

- Dinah.

- Well, Dinah should know.

- Come across the street when you've finished. Miss Hobson's establishment.

- Hobson. Okay.

(Packard 120 car starting and leaving)

- What does thee wish?

- I'm looking for some local bi... What did you say?

[...]